Background and design:
The impossible object I chose was a flexible dinosaur. The reason of it being impossible to produce by traditional processes is because of the inter-locking moving mechanism of it. The file was found on Thingiverse, Flex Dino Keychain.
Part 1: FDM printing
Because of the small scale of the model, the success rate of printing was not very high. The first print was done using the raft structure as the base. The outcome didn’t turn out well. The large contacting area of the raft made it basically impossble to remove the base from the dinosaur.
3D printer OS setup (raft)
Raft stucture that cannot be removed
Therefore, my next approaches were using the brim and skirt structures as the base. The width of the dino was set to 40 mm in order to fit in the gumball. The settings are shown as below:
3D printer OS setup (skirt)
3D printer OS setup (brim)
A total of 8 models were printed, and the best four were chosen to be the final products.
Close view of FDM printers printing dino
General view of FDM printers printing dino
Part 2: SLA printing
For SLA printing, the slicer Preform was used. I used the function of the “One-click print” and a support of a 45-degree tilted strucure was generated. The supports was generated with a lot of rods and contact points on the interlocking parts. The material used was selected to be a medical clear material.
Setting page of the Preform Slicer (For Formlabs SLA printer)
SLA printers printing
After washing and curing it, the printed result looked like this:
SLA printer outcome
A pair of pliers were used to detach the dino from the supports. After cutting all the contacting points, the surface was very rough. As a result, the wire brush was used to smooth out the surface as well as the residues in the grooves.
Wire brush
Final products:
At the end, I have 4 FDM printed dinos and one SLA printed dino. All of them fitted into the gumball capsule.
Final products in the gumball
Successes and limitations:
Successes:
All the prints completed by the FDM printers printed by PLA are perfect without any stiffness while moving. All the interlocking mechanisms work in the smalller scale.
All the supports and bases were completely moved.
Limitations:
Due to the small scale, the print made by SLA printers is stiff and not movable. The properties of resin and the small space left for the interlocking mechanism to move made it impossible to move.
Cost estimations:
Material cost:
3D printing resin: $25/kg * 0.010 kg = $0.25
3D printing PLA: $0.12 + $0.38 + $0.24 = $0.74
Labor costs:
3 hours * $15/hr = $45
Machine time:
FDM printers: 7 hours
SLA printer: 3 hours
(Rental cost ignored)
Total costs: $0.25 + $0.74 + $45 = $45.99
